DE 33 18 420 discloses a device for measuring the length of rods which are stored within the scope of an automated stock management. In this device the respective lengths of the rods are stored in a stock management computer. Thus, a suitable workpiece, whose total length corresponds to the individual pieces to be made, is chosen in an independent manner with the aid of the stock management computer for a subsequent manufacturing order, for instance for processing in a sawing machine. To determine the length of the rod, a length measuring device senses the distance of the front sides of the workpiece from a reference point. The length measuring device has a stop and a slide which is opposite to the stop at a distance and movable relative thereto for pushing the rod to be measured onto the stop. The resultant distance of the slide from the stop corresponds to the length of the workpiece to be measured and is stored in the stock management computer so that it is assigned to the respective workpiece.
It is however disadvantageous that the rod must be brought into a defined position for the measurement, namely into contact with the fixed stop, and a supporting means which supports the rod must at least permit a displacement of the rod in the longitudinal direction and must be arranged accordingly. Moreover, with the known device it is not possible to measure cross sections or to determine a straightness of the rod. Thus, on the one hand, the automated stock management cannot make a distinction between rods of full material, hollow profiles or cornered or round cross-sections, and on the other hand, excessively bent rods might be supplied to the manufacturing process so that required shape tolerance cannot be achieved with such rods, and when preset limit values are exceeded, the rods may cause damage during the storing process or when supplied to the cutting-off machine.
Furthermore, a device is known wherein a measuring roll presses against the rod and is rolled along the rod for determining the length of the rod. At the same time, the setting height of the measuring roll is detected via an NC axis and the thickness of the material is determined. This device, however, has the following disadvantages. First, it is only the height, but not the shape or width of the rod, that can be determined. Second, the length of the rod can only be determined with great tolerance due to different material surfaces, such as round or flat, smooth or scaled surfaces and also due to a rolling of the measuring roll at the rod end during transition from the horizontal movement into the vertical movement. A straightness of the rod can also not be determined with the known device. Moreover, in this device too, the rod must be pushed at one side against a stop, resulting in the above-mentioned disadvantages.